Motor ventilation



Nov. 15, 1949 E. w. HUBSCHER 2,483,409

MOTOR VENTILATION FilecLNov. 30, 1946 9 3 3 f}? j if /7/ WITNESSES: INVENTOR ATTORNEY Patented Nov. 15, 1949 MOTOR VENTILATION Eric W. llubccher, Pittsburgh, Pa accignor to Westinghouse Electric Corporation, Eat Pittaburgh, Pa., a corporation of Pennsylvania Application November 30, 1946, Serial No. 113,272

My invention relates to an improved economical method and means for cooling dynamo-electric machines, and it has particular relation to the cooling of the smaller integral-horsepower sizes of commercial open and protected squirrel-cage motors.

Heretofore, open and protected squirrel-cage motors have been cooled with a single-end ventilating-system, comprising a separate fan or blower which was pressed on the shaft at the exhaust-end of the machine, this blower being disposed inside of the exhaust-end bracket, so that it would discharge its air through the airvent openings in the end of the bracket in which it was located. This construction utilized the fan as an exhaust-blower for drawing air axially through the machine. It was an effective ventilating-meanabut it involved a, fairly large fan, and some more or less costly machining operations, although it suffered the handicap of having eddy-formation, and some loss of pressure-head,

because of the high radial component of the airstream after leaving the blower, in combination with the necessity for bending that air-stream and discharging it through restricted air-vent openings in the end-bracket at that end of the machine.

An object of my present invention is to provide an improved motor-ventilating system in which the conventional air-flow is reversed.

A more specifically stated object of my invention is to provide a single-end-ventilated motor, having a cast squirrel-cage winding having blower-blades cast integrally with one of the endrings of the squirrel-cage structure. in combination with a stationary air-shield or baflle which extends inwardly from the bracket at that end of the machine, so as to force the blower to operate as a pressure-blower. for drawing air into the machine through the bracket-openings at its end, and then forcing the air axially through the machine and expelling it through the bracketopenings at the other end of the machine. The fact that these blower-blades are an integral part of the squirrel-cage casting results in an extremely good heat-flow from the squirrel-cage winding to the blower-blades, and thus makes these blades act as an increased heat-radiating surface for cooling the squirrel-cage winding of the motor, besides ventilating the stator-member in the same manner as the previously used system having a separate blower at the exhaust-end of the machine.

With the foregoing and other objects in view, my invention consists in the elements, parts,

1 Claim. (Cl. 172-46) combinations", structure's d systems hereinafter described and claimed. and illustrated in the accompanying'dra'wing. wherein Figure 1 is a side view, partly in longitudinal section, showing one form of application of my invention. in a squirrel-cage motor; and

Fig. 2 is an end view, with parts broken away.

I have shown my invention as being embodied in a single-end-ventilated squirrel-cage motor or other dynamo-electric 'ma'chine,- comprising a stator-member I and a rotor-member 2. The stator-member i has a rigid framering 3 which constitutes an imperforate enclosure-ring for the machine. The frame-ring 3 supports a laminated stator-core 4 which makes contact with the frame-ring at only a few spaced points 5, around the periphery of the core, thereby providing intermediate, axially disposed, ventilatingducts t between the stator-core and theframe-ring. The stator-core also carries astator-winding'l.

The machine is provided with two brackets 8, one at each end-of the machine. Eachbracket has an imperforate peripheral portion 9 in engagement with an end of the frame-ring 3. Each bracket 8 also has a perforated end-portion [0, having a centrally disposed hearing, I i, and one or more air-vent perforations l2 therein.

The rotor-member 2 has a shaft I! which is rotatably supported in the bearings i I. A rotorcore I4 is provided on the shaft, in operative relation to the stator-core 4. This rotor-core It carries a cast squirrel-cage winding it having a plurality of fan-blades l8, extending out, preferably axially, from one endof the squirrel-cage member l5, and cast integrally therewith. By the word cast," I mean to include brazing or any other forming-process for producing a molecularly integral structure.

In accordance with my invention, the bracket 8 at the fan-end of the machine is provided with an inwardly extending air-shield or baille II, which is connected to the imperforate peripheral part 9 of that bracket, and which extends down into juxtaposition to the ends of the fan-blades II.

In operation, it will be noted that the rotorcore ll is imperforate below the squirrel-cage bars, that is, it has no axially extending ducts therein. This circumstance, in combination with the stationary air-shield l'l, causes the rotorblades to draw air inwardly through the openings ii in the adjacent bracket 8, and then to force the air axially through the stator-ducts 8, and

thence out through the openings in the other.

bracket 8, at the other end of the machine.

As previously intimated in my statement of objects, the construction of the fan-blades II, as integral extensions of the squirrel-cage casting ll, makes these blades operate as extended heatradiating surfaces, for conducting heat directly out of the squirrel-cage element, and transferring it to the air-stream, thus resulting in a more direct rotor-ventilation than was achieved in previous designs. At the same time, the statorelernent is cooled by the end-to-end air-flow through the stator-ducts 0 between the statorcore 4 and the frame-ring I, the same as in the previous designs.

The manufacturing cost of my improved motor is appreciably less than that of the motor which it replaces, and tests have shown that itadequately meets the ventilating-requirements of the smaller sizes of a completely redesigned and rerated line of squirrel-cage motors, in which costreduction, and increased ratings for given irarne sizes, have been coupled with an effort to achieve a pleasing appearance.

While my preliminary tests have had to do primarily with the smaller ratings of this line of motors, it will be understood that my invention is not altogether limited thereto. Furthermore,

while I have illustrated my invention in only one preferred form of embodiment, it should be understood that the invention is susceptible of changes in form and size and shape, and like features. I desire, therefore, that the appended claim shall be accorded the broadest construction consistent with their language.

I claim as my invention:

A squirrel-cage dynamo-electric machine, comprising a stator-member and a rotor-member; said stator-member having a rigid frame-ring constituting an imperforate enclosure-ring, and a stator-core supported by the frame-ring, said stator-core making contact with the frame-ring at only a few spaced points around the periphery of the core, thereby providing intermediate, axial- 4 1y disposed, ventilating-ducts between the statorcore and the frame-ring; a stator-winding carried by the stator-core; a bracket at each end of the machine, each bracket having an imperforate peripheral portion in engagement with an end of the frame-ring, each bracket further having a perforated end-portion having a centrally disposed bearing and having one or more air-vent perforations therein; said rotor-member having a shaft rotatably supported in said bearings, and having a rotor-core carried by said shaft in operative relation to the stator-core; a molecularly integral squirrel-cage winding carried by the rotor-core, having a plurality of fan-blades extending out from one end of the squirrel-cage member and formed molecularly integrally therewith; and an air-shield connected to the imperforate peripheral part of the bracket at said fanend of the machine, said air-shield extending down into juxtaposition to the fan-blades; said rotor-core being irnperforate below the squirrelcage bars, whereby the fan draws air inwardly through the adjacent bracket, and forces it axially through the statorducts and thence out through the other bracket.

ERIC W. HUBSCHER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,300,373 Garcelon Apr. 15, 1919 1,304,229 Wiard May 20, 1919 1,852,476 Pfleger Apr. 5, 1932 1,920,315 Myers Aug. 1, 1933 2,100,020 Andrews Nov. 23, 1937 2,286,750 McMahan June 16, 1942 2,401,662 Divi June 4, 1946 

